I remember the fate of Iraq's WMD (chemical) -- they denied inspectors, blatantly lied on the reports for many years. It was all way too suspicious, but their biggest trick was that when UN approved a military intervention, no WMDs were actually found. That put US in a very bad position because they couldn't prove WMDs existense. Who knows, maybe there were really no WMDs (or just hidden well).
However, unlike chemical substances, radiation is easily detectable even in minuscule quantities. Just transporting radioactive materials leave a detectable trace, so I bet they won't be lost for long. The only way to actually hide them is to contaminate the whole area with the same materials.
However, unlike chemical substances, radiation is easily detectable even in minuscule quantities. Just transporting radioactive materials leave a detectable trace, so I bet they won't be lost for long. The only way to actually hide them is to contaminate the whole area with the same materials.